Any food can be made low calorie by eating less of it. Fat has twice the calories per gram so anything with higher fat will be a very small quantity. Take nuts for example. Weigh out a 100 calories. By comparison weigh out 100 calories of air popped popcorn.

High protein are all the meats, and eggs. There is tofu and powdered supplements too.

A nice quick high protein low calorie breakfast would be a hard boiled egg.

For lunch, how about canned tuna, cooked cubed chicken breast or baked tofu cubes over a bed of Romaine? Add any other veggies of your choice.

Stews and soups are lower calorie because of the water. You can buy ready made if you are short on time. Or you can buy a ready roasted chicken at the store and make a soup from the bones. Again, add the veggies of your choice.